Grav Deck

The Grav Deck, short for Gravity Deck is the one of two ways to create "artificial" gravity for spacecraft in the BattleTech universe.


With the BattleTech universe lacking any advanced "science-fiction" means of creating gravity aboard spacecraft, the two options are the real-world options of reaction gravity and centrifugal gravity.

Reaction gravity is the primary form of gravity generation used by DropShips, with gravity emulated in the opposite direction to the direction of thrust. Save for the flip-over at the halfway point, generally a DropShip in flight will always be under thrust and thus generate some degree of gravity for the health of the crew.

For larger vessels such as JumpShips and WarShips which have to spend time effectively motionless so as to charge their Jump Drives, and relatively stationary objects such as Space Stations which lack engines large enough to generate reaction gravity, a Grav Deck is carried. A ring-shaped section that produces gravity by rotating around the axis of the ship or station and so acts like an enormous centrifuge, as the grav deck spins, the centrifugal force pushes objects outward from the deck's center and the deck's wall becomes the "floor".

In general, only the largest WarShips or Space Stations have multiple grav decks, and most JumpShips and smaller vessels generally devote their limited space to recreation and exercise areas for the crew and passengers, and for medical bays for patients with conditions worsened by prolonged exposure to zero-gravity. Some smaller crew on vessels may refurbish their grav decks to allow rooms to be built as quarters (the Merchant is specifically noted for such customization).[1] Aboard larger vessels, the size of the crew will be many times the available space on the Grav Deck, so rosters are generally used to ensure access to the grav decks is evenly split, which can become a sore point on prolonged voyages.

Grav decks are locked when not at station keeping, as any use under acceleration will cause the deck to malfunction. Failed motor bearings putting out of commission such an important piece of the vessel to crew morale ensure the avoidance of any such noise or vibration failures.[1]

Grav decks are available in many sizes, but for convenience, they are typically divided into one of three classes. Small grav decks are less than 100 meters in diameter, weigh 50 tons[2], and cost 5,000,000 C-bills. A medium grav deck's diameter is between 100 and 250 meters, weighs 100 tons[2], and costs twice as much as a small grav deck. A large grav deck is any grav deck with a diameter over 250 meters, weighing in at 500 tons[2]. These mammoth constructions cost 40,000,000 C-bills and are usually included only in the largest space stations.[3][4]


  1. 1.0 1.1 DropShips and JumpShips: ComStar Intelligence Summary, p. 18
  2. 2.0 2.1 2.2 Tactical Operations, p. 407: "Heavy Weapons and Equipment Construction Data Table"
  3. Strategic Operations, p. 159: "Advanced Aerospace Unit Costs Tables"
  4. Tactical Operations, pp. 314–315: "Grav Deck"